1. Field of the Invention
The present invention relates to signal conversion and, more particularly, to circuitry for converting a differential input signal to a single-ended output signal without the use of an operational amplifier.
2. Description of Related Art
Differential to single-ended converters, which are well known in the art, are used to convert a differential input signal to a single-ended output signal. Typical prior art differential to single-ended converters are described and shown in "Bipolar and MOS Analog Integrated Circuit Design", Alan B. Grebene, pages 310-316.
Grebene's page 313 shows the basic connections for a single-ended output converter design, which is also shown in FIG. 1 of this document.
A primary disadvantage of these previously-known differential to single-ended converters is that each requires an operational amplifier. As is known, op amps have a variety of inherent drawbacks. They are complex circuits that use a large silicon area. They are somewhat unreliable and unpredictable in operation. It is difficult to manufacture them such that they are environment-independent, that is, so that they operate consistently over a wide temperature range, for example. Furthermore, their common mode voltages are not sufficiently reliable.
What is desirable, therefore, is a new and improved differential to single-ended converter which does not require an op amp, and which is small, inexpensive, reliable and predictable. It is also desirable that this new differential to single-ended converter by readily adaptable or programmable to offer a variety of operating characteristics without requiring dramatic alteration of the fabrication process or mask layout.